material definition in workbench

[folle76]

Hello.
would you kindly tell me if it is enough to define how from images the material and type of analysis to perform an analysis with elastic-linearly plastic material? If yes, how come the maximum voltage if it goes well above the 460 mpa? Where am I wrong?
Thank you.

 

[stefano.garbin]

"uniaxial test data" is simply a collection of sigma-epsilon points that is not used in simulation. you must, in "engineering data", insert a model of non-linear material. of these models there are an infinity depending on the needs.
put that for example you want to simulate a steel with the following features:
e=200000 mpa
sigma_s=500 mpa (steel)
sigma_r=700 mpa (rupture voltage)
epsilon_r=0.1 (breaking stretch of 10%)
you can use a "near isotropic hardening" model.
What does that mean?
until the voltage is lower than the yield the response of the material is linear according to the law sigma=e*epsilon
when the tension exceeds the slope of the sigma-epsilon curve changes (there is a step) and continues with slope t (which is also called "tangent modulus"), where it has that=(sigma_r-sigma_s)/(epsilon_r-epsilon_s)as epsilon_s=sigma_s/ethen we have=(sigma_r-sigma_s)/(epsilon_r-(sigma_s/e)with a model of this type if the tension exceeds that of break the slope of the sigma-epsilon curve always remains "t", and therefore we do not have a perfectly plastic behavior (that if you work with forces imposed instead of movements imposed often and willingly gives you a lot of problems.
summing up a bilinear model requires only this information:
1-module of young (e)
2-module of poisson (nu)
3-steel stress (sigma_s)
4-module tangent (t)
once correctly defined the material, when you make the simulation always remember in "analysis settings" to choose "large deflections = on" otherwise ansys does not take into account non-linearity.

 

[folle76]

What to say... if they make ansys festival your cachet can safely exceed that of celentan. Thank you very much!!! !

 

[stefano.garbin]

It would be enough for me what he takes in an evening. .
and I could extinguish the mortgage and buy myself a holiday cottage! ;-)
Thank you!

 

[700Hz]

"uniaxial test data" is simply a collection of sigma-epsilon points that is not used in simulation. you must, in "engineering data", insert a model of non-linear material. of these models there are an infinity depending on the needs.
put that for example you want to simulate a steel with the following features:
e=200000 mpa
sigma_s=500 mpa (steel)
sigma_r=700 mpa (rupture voltage)
epsilon_r=0.1 (breaking stretch of 10%)
you can use a "near isotropic hardening" model.
What does that mean?
until the voltage is lower than the yield the response of the material is linear according to the law sigma=e*epsilon
when the tension exceeds the slope of the sigma-epsilon curve changes (there is a step) and continues with slope t (which is also called "tangent modulus"), where it has that=(sigma_r-sigma_s)/(epsilon_r-epsilon_s)as epsilon_s=sigma_s/ethen we have=(sigma_r-sigma_s)/(epsilon_r-(sigma_s/e)with a model of this type if the tension exceeds that of break the slope of the sigma-epsilon curve always remains "t", and therefore we do not have a perfectly plastic behavior (that if you work with forces imposed instead of movements imposed often and willingly gives you a lot of problems.
summing up a bilinear model requires only this information:
1-module of young (e)
2-module of poisson (nu)
3-steel stress (sigma_s)
4-module tangent (t)
once correctly defined the material, when you make the simulation always remember in "analysis settings" to choose "large deflections = on" otherwise ansys does not take into account non-linearity.

Hello stefano,
I reconnect to this post for a doubt I was researching these days.
I also use bilinear curves on wb and doubt is as follows: is it correct to use the calculations quoted by you in the quoted post to get the curve?
what I mean is that usually when you find the properties of the materials, you will find the rm (tensile strenght) and the ruptured elongation to%, which however do not correspond by force in the graph epsilon/sigma!
In fact the iso 6892-1 speaks clearly of elongation after breaking and elongation to the max load (which would be stretching at the point where we have rm). only that usually in the norms of the various metal materials are rm and a% (extension after break) and the tension in the epsilon/sigma chart at a% is usually different from rm...
so my doubt would be: is it correct to create a graph (and therefore a tangent module) relationing rm with elongation after break?

thanks (to all) for the opinion!

Hi!